Although the GitHub docs contains good info on how to add an existing GitHub project to your local machine, how to add an existing (unversioned) project from your local machine to GitHub was a little less clear to me. Here are the steps I use.

From IntelliJ

Select ‘VCS’ menu -> Import in Version Control -> Share project on GitHub.

In the latest version (v13) of IntelliJ, you will then be prompted for which files you wish to include as part of the initial commit. Obviously deselect anything in the target (aka classes) folder. I also exclude the .idea folder. Click OK and you new project and files should now be available via GitHub!

In older versions of IntelliJ, this step (somewhat strangely) created the project with just the readme. Follow the the next step to add the other files.

I think: git remote add origin git@github.com:username/projectname.git does the same thing.

The ‘origin’ name is arbitrary (As with branch naming, remote alias names are arbitrary – just as ‘master’ has no special meaning but is widely used because git init sets it up by default, ‘origin’ is often used as a remote name because git clone sets it up by default as the cloned-from URL. You can really name it just about anything.)